remove xml dependency from client

lib/client.dart

@@ -2,7 +2,6 @@ import 'dart:async';
 
 import 'package:http/http.dart' as http;
 import 'package:webfeedclient/domain/rss_feed.dart';
-import 'package:xml/xml.dart' as xml;
 
 class WebFeedClient {
   http.Client client;
@@ -17,8 +16,7 @@ class WebFeedClient {
       print("Response Body: ${response.body}");
       return response.body;
     }).then((bodyString) {
-      var document = xml.parse(bodyString);
-      var channel = new RssFeed.parse(document);
+      var channel = new RssFeed.parse(bodyString);
       return channel;
     });
   }

lib/domain/rss_feed.dart

@@ -45,7 +45,8 @@ class RssFeed {
       this.webMaster,
       this.ttl});
 
-  factory RssFeed.parse(XmlDocument document) {
+  factory RssFeed.parse(String xmlString) {
+    XmlDocument document = parse(xmlString);
     XmlElement channelElement;
     try {
       channelElement = document.findAllElements("channel").first;

test/rss_test.dart

@@ -7,18 +7,16 @@ import 'package:xml/xml.dart' as xml;
 void main() {
   test("parsing Invalid.xml", () {
     var xmlString = new File("test/xml/Invalid.xml").readAsStringSync();
-    var doc = xml.parse(xmlString);
 
     try {
-      new RssFeed.parse(doc);
+      new RssFeed.parse(xmlString);
       fail("Should throw Argument Error");
     } on ArgumentError {}
   });
   test("parsing RSS.xml", () {
     var xmlString = new File("test/xml/RSS.xml").readAsStringSync();
-    var doc = xml.parse(xmlString);
 
-    var feed = new RssFeed.parse(doc);
+    var feed = new RssFeed.parse(xmlString);
 
     expect(feed.title, "News - Foo bar News");
     expect(feed.description, "Foo bar News and Updates feed provided by Foo bar, Inc.");